NASA's Planetary Science Decadal Survey has concluded that isotopic measurements of cometary water vapor are a means to unraveling the mysteries involving the origin of Earth's water and the evolution of our solar system. To support this, a recent Jet Propulsion Laboratory internal research program has developed quantum limited superconductor-insulator-superconductor (SIS) receivers in the important 500-600 GHz submillimeter frequency band. These instruments can be used to detect the deuterated water (HDO) ground state (110-101), H216O ortho ground state (110-101), and the oxygen isotopologues H217O and H218O with exquisite sensitivity. To achieve the presented results, we have investigated aluminum oxide (AlOx) and aluminum nitride (AlNx) barrier SIS tunnel junction mixers on the 6-μm silicon-on-insulator substrate. The AlOx and AlNx junction mixer blocks utilize diagonal and smooth-profile conical horns, respectively. In both cases, a commercial 4-8-GHz intermediate frequency low-noise amplifier (LNA) has been integrated into the mixer block. The AlOx (low-current-density) barrier SIS junctions were fabricated with 2-μm gold beam-lead technology, whereas in the case of the AlNx SIS tunnel junction, we use capacitive RF decoupling tabs. The latter approach simplifies fabrication, increases yield, eases the mounting process, and facilitates scaling to higher frequencies. For an actual flight mission, with operation ≤4.2 K, the allowed heat dissipation of the mixer-integrated LNA needs to be minimized. In this article, we also investigate the receiver sensitivity as a function of the LNA dc power consumption. We find that the dc power consumption of the LNA can be reduced to ~1.6 mW with minimal loss in sensitivity. It is anticipated that the continued InP HEMT development for quantum computer applications are likely to reduce the required LNA power dissipation even further.

中文翻译：

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用于检测彗星水同位素发射的量子有限 SIS 接收器技术


美国宇航局行星科学十年调查得出的结论是，彗星水蒸气的同位素测量是解开地球水起源和太阳系演化之谜的一种手段。为了支持这一点，喷气推进实验室最近的一项内部研究计划在重要的 500-600 GHz 亚毫米频段开发了量子受限超导体-绝缘体-超导体 (SIS) 接收器。这些仪器可用于检测氘化水（HDO）基态（110-101）、H216O邻基态（110-101）以及氧同位素体H217O和H218O，具有极高的灵敏度。为了实现所提出的结果，我们研究了 6 μm 绝缘体上硅衬底上的氧化铝 (AlOx) 和氮化铝 (AlNx) 势垒 SIS 隧道结混频器。 AlOx 和 AlNx 接合混合器块分别采用对角线和光滑轮廓的锥形喇叭。在这两种情况下，商用 4-8 GHz 中频低噪声放大器 (LNA) 均已集成到混频器模块中。 AlOx（低电流密度）势垒 SIS 结采用 2 μm 金梁引线技术制造，而对于 AlNx SIS 隧道结，我们使用电容式射频去耦片。后一种方法简化了制造，提高了产量，简化了安装过程，并有利于扩展到更高的频率。对于实际飞行任务，在运行温度≤4.2 K 的情况下，需要最大限度地减少集成混频器的 LNA 的允许散热量。在本文中，我们还研究了接收器灵敏度与 LNA 直流功耗的函数关系。我们发现 LNA 的直流功耗可降低至约 1.6 mW，同时灵敏度损失最小。 预计量子计算机应用中 InP HEMT 的持续开发可能会进一步降低所需的 LNA 功耗。